Thermal barrier and cooling air deflector for totally enclosed motor

ABSTRACT

The present invention provides for a system and method for facilitating cooling of a totally enclosed motor. A first thermal barrier is coupled to a first end bracket and is operable to insulate bearings from internal heat produced by the motor. Either an external fan located opposite the drive end of the motor, an externally mounted blower, or free ambient air convection may be employed to provide cooling air to the motor. An air deflector is coupled to the drive end of the motor to capture the cooling air and direct it as high velocity air over the first end bracket thereby keeping the bearings supported within the first end bracket cool. Alternatively, an external fan may be coupled to the drive end of the motor to provide cooling air to the first end bracket.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.09/878,527 entitled “THERMAL BARRIER AND COOLING AIR DEFLECTOR FORTOTALLY ENCLOSED MOTOR” and filed Jun. 11, 2001, now U.S. Pat. No.6,734,584 the entirety of which is incorporated by reference.

TECHNICAL FIELD

The present invention generally relates to totally enclosed motors andin particular to a system and method of facilitating cooling of internalcomponents of a totally enclosed motor.

BACKGROUND OF THE INVENTION

Electric motors generate heat during operation as a result of bothelectrical and mechanical losses, and an electric motor typically mustbe cooled in order to ensure the desired and efficient operation of themotor. An excessively high motor temperature may result in motor bearingfailure or damage to the stator winding insulation. Electric motorsgenerally have an enclosure, or housing, including a frame and endbrackets. Some of the most common enclosures include open enclosures andtotally enclosed enclosures. With an open enclosure, ambient aircirculates within the enclosure, and heat is removed by convectionbetween the air and heat generating motor components within theenclosure. The heated air is exhausted out from the enclosure.

Totally enclosed type enclosures typically are used in applications inwhich airborne contaminants (e.g., dirt, oil, or mist), must beprevented from entering within the enclosure. There is no communicationof air through the enclosure and thus no possibility of bringing coolingair from outside the enclosure into the interior. Both convection andconduction type cooling occurs within the enclosure, and some form ofconvection cooling occurs at the external surfaces of the enclosure. Forexample, a fan mounted to the motor shaft provides forced convectioncooling. The fan forces air over the frame and end brackets. However,this system can be unsatisfactory to cool the bearings. The heating ofthe bearing is primarily the result of the air inside the motor that iselevated in temperature by the heat generated by the rotor and statorwindings and friction losses in the bearing.

The prior art has attempted to cool bearings in totally enclosed motorsby cooling an outside surface thermally coupled to the bearing by anexternal shaft fan. The arrangement was unsatisfactory since theexternal fan was noisy, reduced motor efficiency and was often coveredby a customer coupling guard. The prior art has attempted to circulatethe air internal the motor. This was also unsatisfactory since there waslittle transfer of heat from the inside of the motor to an outsideambient. Circulation of the internal air, which is elevated intemperature, is totally inadequate to cool the bearing. Other methodsattempted by the prior art include enlarging the case for more coolingsurface area, rating the motors for a lower power rating for a given fanRPM.

Therefore, there is an unmet need in the art to provide improvements incooling of the bearings of totally enclosed motors for maintaining thereliability of the motor during normal operations.

SUMMARY OF THE INVENTION

The following presents a simplified summary of the invention in order toprovide a basic understanding of some aspects of the invention. Thissummary is not an extensive overview of the invention. It is intended toneither identify key or critical elements of the invention nor delineatethe scope of the invention. Its sole purpose is to present some conceptsof the invention in a simplified form as a prelude to the more detaileddescription that is presented later.

The present invention provides for a system and method that facilitatescooling of the bearings of a totally enclosed motor. The totallyenclosed motor of the present invention includes a cylindrical framecoupled to a first circular end bracket and a second circular endbracket. The first end bracket is located at a drive end of the motorwhile the second end bracket is located opposite the drive end of themotor. Within the frame is an electrical core for providing energy tothe motor. The electrical core consists of a stator, a rotor, and anyadditional circuitry and wiring required to operate the motor. The rotoris mounted on a rotor shaft. The rotor shaft assembly is supported bybearing assemblies located in both the first end bracket and second endbracket. The stator and rotor produces heat while providing energy tothe motor. The present invention provides for a system and method ofproviding cooling air in addition to isolating at least one of thebearings to improve bearing life.

According to one aspect of the present invention, an improved coolingsystem for a totally enclosed motor includes a first thermal barriercoupled to the first end bracket and operable to insulate the bearinglocated at the drive end of the motor. Either an external fan locatedopposite the drive end of the motor or an externally mounted blower maybe employed to provide cooling air to the motor. Moreover, a secondthermal barrier operable to insulate bearings located opposite the driveend of the motor may be coupled to the second end bracket.

According to another aspect of the present invention, an improvedcooling system for a totally enclosed motor includes an air deflectorcoupled to the drive end of the motor. The air deflector is operable tocapture the cooling air provided by the external fan or the blower anddirect it as high velocity air over the first end bracket, therebykeeping the bearing supported within the first end bracket cool.Alternatively, an external fan may be coupled to the drive end of themotor to provide cooling air to the first end bracket.

To the accomplishment of the foregoing and related ends, the inventionthen, comprises the features hereinafter fully described andparticularly pointed out in the claims. The following description andannexed drawings set forth in detail certain illustrative embodiments ofthe invention. These embodiments are indicative, however, of but a fewof the various ways in which the principles of the invention may beemployed. Other object, advantages and novel features of the inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a cross-sectional view of a totally enclosed fancooled motor in accordance with one aspect of the present invention;

FIG. 2 illustrates a front view of a thermal barrier in accordance withone aspect of the present invention;

FIG. 3 illustrates a cross-sectional view of the thermal barrier of FIG.2 along the lines A—A in accordance with one aspect of the presentinvention;

FIG. 4 illustrates a front view of an air deflector in accordance withone aspect of the present invention;

FIG. 5 illustrates a side view of the air deflector of FIG. 4 inaccordance with one aspect of the present invention;

FIG. 6 illustrates a cross-sectional view of a totally enclosed fancooled motor utilizing an external airflow source in accordance with oneaspect of the present invention;

FIG. 7 illustrates a cross-sectional view of a totally enclosed motorutilizing in accordance with one aspect of the present invention;

FIG. 8 illustrates a cross-sectional view of a totally enclosed motoremploying non-ventilated cooling in accordance with one aspect of thepresent invention;

FIG. 9 illustrates a flow diagram of a methodology of manufacturing atotally enclosed motor in accordance with one aspect of the presentinvention; and

FIG. 10 illustrates a flow diagram of a methodology of cooling a totallyenclosed motor in accordance with one aspect of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described with reference to thedrawings. The present invention provides for a system and method thatfacilitates cooling of the bearings of a totally enclosed motor. Thetotally enclosed motor can be provided with a fan at an opposite driveend of the motor for cooling the motor. Alternatively, a blower may beprovided at the opposite drive end of the motor for cooling the motor.The totally enclosed motor may also be cooled by convection as anon-ventilated motor. The present invention will also be described withreference to a methodology for employing the system.

FIG. 1 illustrates an example of a system for facilitating cooling ofinternal components of a totally enclosed fan cooled (TEFC) motor inaccordance with one aspect of the present invention. A TEFC motor 10 hasa generally cylindrical frame 20 surrounding a motor core 25. The motorcore 25 converts electrical energy to mechanical energy to driveexternal devices coupled to the motor 10. The motor core 25 is comprisedof a stator 40 and a rotor 50. The rotor 50 is coupled to a shaft 60extending through a central longitudinal axis of the motor 10. Duringoperation of the motor 10, electrical current is provided to the statorwindings, which generates a magnetic field that induces a current in thewindings of the rotor. The induced current in the windings alsogenerates a magnetic field that follows the rotating magnetic fieldgenerated from the windings of the stator and causes the rotor 50 torotate, thus, rotating the shaft 60. During operation of the motor 10,heat is generated from the windings of both the stator 60 and the rotor50 within the motor core 25. The shaft 60 is supported by a firstbearing assembly 70 located at a drive end of the motor 10 and a secondbearing assembly 80 located at an opposite end of the drive end of themotor 10. The heat generated from the core 25 of the motor 10 heats theair inside the motor 10. The heated air has a deleterious effect on theefficient operation and life of the bearing assemblies 70 and 80.Additionally, the heat generated by the core 25 has a deleterious effecton the efficiency of the motor 10.

The frame 20 is formed from cast iron or the like and can be molded as asingle integral piece or assembled as multiple pieces. The frame 20includes a plurality of radial extending fins 30 substantially coveringthe frame 20. The bearing assemblies 70 and 80 are generally supportedby circular end brackets 90 and 100, generally referred to as end bellsor end shields. The circular end brackets may also include axiallyextending fins 102 and 104 similar to the motor fins 30. The circularend brackets 90 and 100 and cylindrical frame 20 totally enclose thestator 40 and rotor 50. The fins 30, 102 and 104 add surface area anddirect air over the frame 20 to provide cooling to the motor core 25 andthe bearing assemblies 70 and 80. Inner caps 110 and 120 are coupled toan inner surface of the end brackets 90 and 100, respectively, and areemployed to secure the bearings 70 and 80 in place.

One end of the shaft 60 supports an external fan 130. The fan issurrounded by an enclosure 160 mounted to the opposite drive end of themotor 10. The fan 130 is employed to provide cooling air over the motor10. The cooling air flows over an outside surface of the circular endbracket 100 providing cooling to the bearing assembly 80. The coolingair also flows over the motor fins 30 in the direction of the arrowsalong an outer surface of the frame 20 and around the motor fins 30.Some of the cooling air is captured by an air deflector 150 coupled tothe drive end of the TEFC motor 10, so that the air can be channeled tocool an outside surface of the circular end bracket 90 through endbracket fins 102, as well as the bearings 70 enclosed within the endbracket 90.

Since the fan 130 is present at the opposite drive end of the motor 10,the motor 10 experiences a temperature gradient from one end to theother end, such that the cooling at the drive end is less than at theopposite drive end. Therefore, it is common in the art to mount anexternal fan (not shown) to the drive end of the motor to keep thetemperature gradient at a minimum. However, with this external fansystem, a temperature gradient between the two ends of the motor stillexists. This inability to sufficiently cool the drive end bearings 70may limit the rating of the motor.

Thus, in accordance with one aspect of the present invention, the TEFCmotor 10 also includes a thermal barrier 140 for insulating the bearingassembly 70 from the heat generated by the motor core 25. The thermalbarrier 140 is mounted to an inside surface of the inner cap 110 and theend bracket 90. The thermal barrier 140 is adapted to cover asubstantial portion of the inner cap 100 and the end bracket 90 that isexposed to the internal air of the motor 10. Since the bearings 70 areencased within the inner cap 110 and the end bracket 90, the thermalbarrier 140 acts to insulate the bearings 70 from the heated internalair of the motor 10. This provides for a reduced operating temperatureand increased life of the bearings 70. Alternatively, a thermal barriermay be coupled to any other part of the motor 10, such as the motorframe 20, as long as it acts to insulate the bearings 70 from the heatproduced by the electrical core 25.

FIGS. 2-3 illustrate a thermal barrier 140 in accordance with one aspectof the present invention. FIG. 2 illustrates a front view of the thermalbarrier 140, while FIG. 3 illustrates a cross-sectional view of thethermal barrier 140 along the lines A—A. The thermal barrier 140comprises three parts: an annular inner cap thermal barrier 146; anannular end bracket thermal barrier 142; and an annular gasket 144. Theinner cap thermal barrier 146 includes a circular central opening 148,so that the shaft 60 can extend through the thermal barrier 140. Theinner cap thermal barrier 146 and the end bracket thermal barrier 142are adapted to insulate the inner cap 110 and the end bracket 90 fromthe internal air of the motor 10, so that heat is kept off the bearings70. The inner cap thermal barrier 146 includes apertures 145 formounting the inner cap thermal barrier 146 to the inner cap 110. The endbracket thermal barrier 142 includes apertures 143 for mounting the endbracket thermal barrier 142 to the inner surface of the end bracket 90.The inner cap thermal barrier 146 and the end bracket thermal barrier142 may be made of any material (e.g., fiberglass, metal) suitable towithstand the heat of the motor and provide a sufficient thermal barrierbetween the internal air of the motor and the inner cap 110 and endbracket 90.

For example, in some applications space heaters are mounted to the innercaps 110 and 120 to prevent condensation from forming when the motor isnot energized. In this application, metal is preferred to fiberglass dueto its ability to withstand higher temperatures than fiberglass. It isto be appreciated that the choice of material may differ according tothe particular industrial application of the motor. Although the thermalbarrier is illustrated as being formed of two or more separate parts, itis to be appreciated that the thermal barrier may be manufactured as asingle integral part.

The gasket 144 is utilized to create an airtight seal between the innercap thermal barrier 146 and the end bracket thermal barrier 142 matingparts. This airtight seal is important to keep the internal air of themotor 10 off the bearings 70 and/or end bracket 90. The gasket 144 isalso operable to account for variations in tolerance present in theinner cap thermal barrier 146 and the end bracket thermal barrier 142.The gasket 144 may be of any suitable material able to withstand theheat generated by the motor 10 and provide a seal between the matingparts of the thermal barrier 140. Examples of such material include apolymeric resin that can withstand the heat generated by the core 25 ofthe motor 10, such as vinyl-ester resin or VITON® developed by DuPont.

The gasket 144 is mounted to the inner cap thermal barrier 146 and theend bracket thermal barrier 142 by employing an epoxy such as aepichlorohydrin material rated to withstand the heat generated by themotor core 25. The gasket 144 is mounted to the inner cap thermalbarrier 146 and the end bracket thermal barrier 142 after the inner capthermal barrier 146 and the end bracket thermal barrier 142 are mountedto the inner cap 10 and the end bracket 90, so that the gasket cancompensate for any tolerance variations in the inner cap 110 and the endbracket 90. However, if a thermal barrier is employed as a single pieceor the mating parts are sufficient to create an airtight barrier betweenthe bearings 70 and the internal air of the motor 10, the gasket 144will not be necessary.

FIGS. 4 and 5 illustrate an air deflector 150 in accordance with oneaspect of the present invention. FIG. 4 illustrates a front view of theair deflector 150, while FIG. 5 illustrates a side view of the airdeflector. The air deflector 150 is adapted to be secured to the driveend of the motor. In the present invention, the air deflector 150 isshown as one piece that substantially covers the drive end of the motor10. The air deflector 150 is formed of an annular flat portion 152 andan outwardly extending semicircular portion 154. The annular flatportion 152 is adapted to mount to and cover the drive end of the motor10 (e.g., the end bracket 90). The outwardly extending semicircularportion 154 is adapted to extend along the outer circumference of theframe 20, so that cool air from the fan can be channeled to the outsidesurface of the end bracket 90. The air deflector 150 includes a circularcentral opening 158, so that the shaft 60 can extend through the airdeflector 150. The air deflector 150 includes apertures 156 for mountingthe air deflector 150 to the drive end of the motor 150.

Materials used to manufacture the air deflector 150 may includefiberglass, cast-iron or sheet metal depending upon the environment thatthe motor 10 will be employed. However, the air deflector 150 may bemanufactured from any other material able to withstand various customerindustries and applications. Furthermore, although the air deflector150, as described, is generally one complete part, it may be two or moreparts and still be contemplated as falling within the scope of thepresent invention.

FIG. 6 illustrates another aspect of the present invention. A system forimproved cooling of a TEFC motor 210 includes a thermal barrier 340disposed inside the motor 210 for insulating a drive side bearingassembly 270 from the heat generated by a motor core 225. The TEFC motor210 has a generally cylindrical frame 220 surrounding the motor core225. The motor core 225 is comprised of a stator 240 and a rotor 250.The rotor 250 is coupled to a shaft 260 extending through a centrallongitudinal axis of the motor 210. The shaft 260 is supported by thebearing assembly 270 located at a drive end of the motor 210 and abearing assembly 280 located at opposite end of the drive end of themotor 210. The frame 220 includes a plurality of radial extending fins230 substantially covering the frame 220. The bearing assemblies 270 and280 are generally supported by circular end brackets 290 and 300, andinner caps 310 and 320 coupled to the end brackets 290 and 300,respectively. The circular end brackets 310 and 320 also include axiallyextending fins 302 and 304 similar to the motor fins 230. One end of theshaft 260 supports an external fan 330. The external fan 330 issurrounded by an enclosure 360 disposed at an opposite drive end of themotor 210. The fan 330 is employed to provide cooling air to the motor210.

The thermal barrier 340 is mounted to the inner cap 310 and adapted tocover a substantial portion of the inner cap 310 and the end bracket 290that is exposed to the internal air of the motor 210. Since the bearings270 are encased within the inner cap 310 and the end bracket 290, thethermal barrier 340 acts to insulate the bearings 270 from the heatedinternal air of the motor 210. This provides for a reduced operatingtemperature and increased life of the bearings 270. The system does notemploy an air deflector like the system of FIG. 1, but utilizes anexternal air source 335 for cooling the drive end of the motor. Theexternal air source 335 can be an external shaft mounted fan or anexternal blower. Alternatively, the drive end of the motor can be cooledby convection, such that the external air source 335 is air from theenvironment surrounding the motor 210.

FIG. 7 illustrates yet another aspect of the present invention. When anexternal fan is present in a totally enclosed motor, it is generallycoupled to the rotor shaft, as described in FIG. 1 and FIG. 6. Thus, thespeed of the fan is dependent on the speed of the motor. In variablespeed motors, the motor does not cool as well utilizing an external fandue to the constant changes in speed. For instance, when the speed ofthe fan decreases in response to a decrease in motor speed, the coolingeffect of the fan decreases. In order to provide cooling air to themotor at variable speeds, a blower 530 may be employed in lieu of thefan. The fan may or may not be present in the motor.

FIG. 7 illustrates a system for facilitating cooling of a totallyenclosed motor 410. The totally enclosed motor 410 has a generallycylindrical frame 420 surrounding a motor core 425. The motor core 425is comprised of a stator 440 and a rotor 450. The rotor 450 is coupledto a shaft 460 extending through a central longitudinal axis of themotor 410. The shaft 460 is supported by a bearing assembly 470 locatedat a drive end of the motor 410 and a bearing assembly 480 located atopposite end of the drive end of the motor 410. The frame 420 includes aplurality of radial extending fins 430 substantially covering the frame420. The bearing assemblies 470 and 480 are generally supported bycircular end brackets 490 and 500, and inner caps 510 and 520 coupled tothe end brackets 490 and 500, respectively. The circular end brackets490 and 500 may include axially extending fins 502 and 504 similar tothe motor fins 530.

The motor 410 includes a thermal barrier 540 disposed inside the motor410 for insulating the drive side bearing assembly 470 from the heatgenerated by the motor core 425. The thermal barrier 540 is mounted tothe inner cap 510 and is adapted to cover a substantial portion of theinner cap 510 and the end bracket 490 that are exposed to the internalair of the motor 410. Since the bearings 470 are encased within theinner cap 510 and the end bracket 490, the thermal barrier 540 acts toinsulate the bearings 470 from the heated internal air of the motor 410.The motor 410 can also include a thermal barrier 570 disposed inside themotor 410 for insulating a non-drive side bearing assembly 480 from theheat generated by the motor core 425. The thermal barrier 570 isprovided to ensure that the opposite drive side of the motor 410 remainscool in absence of a fan for providing cooling directly to the oppositedrive side of the motor 410. The thermal barrier 570 is mounted to theinner cap 520 and is adapted to cover a substantial portion of the innercap 520 and the end bracket 500 that is exposed to the internal air ofthe motor 410. Since the bearings 480 are encased within the inner cap520 and the end bracket 500, the thermal barrier 570 acts to insulatethe bearings 480 from the heated internal air of the motor 410.

The blower 530 provides airflow down the frame 420 of the motor 410 toan air deflector 550. The blower 530 is attached to an enclosure 560located at the opposite drive end of the motor 410. It is to beappreciated that the blower 530 may be attached to some other structurebesides the motor 410. The blower 530 provides cool air along theexternal frame 420 at a constant velocity regardless of the operatingspeed of the motor 410. Cooled air from the blower 530 flows throughchannels formed by the fins 430 over the external frame 420 of the motor410. The air deflector 550 captures a portion of the external cooled airand directs it as high velocity air over the end bracket 490, therebykeeping the drive end bearings 470 cool. It is to be appreciated that analternate means for cooling the drive end, such as an external fan, maybe used instead of the air deflector 550.

FIG. 8 illustrates yet another aspect of the present invention whereinexternal airflow sources are provided on both the drive side of atotally enclosed motor 610 and the opposite drive side of the totallyenclosed motor 610. The totally enclosed motor 610 has a generallycylindrical frame 620 surrounding a motor core 625. The motor core 625is comprised of a stator 640 and a rotor 650. The rotor 650 is coupledto a shaft 660 extending through a central longitudinal axis of themotor 610. The shaft 660 is supported by a bearing assembly 670 locatedat a drive end of the motor 610 and a bearing assembly 680 located at anopposite end of the drive end of the motor 610. The frame 620 includes aplurality of radial extending fins 630 substantially covering the frame620. The bearing assemblies 670 and 680 are generally supported bycircular end brackets 690 and 700, and inner caps 710 and 720 coupled tothe end brackets 690 and 700, respectively. The circular end bracketsmay include axially extending fins 702 and 704 similar to the motor fins630.

The motor 610 includes a thermal barrier 740 disposed inside the motor610 for insulating the drive side bearing assembly 670 from the heatgenerated by a motor core 625. The thermal barrier 740 is mounted to theinner cap 710 and adapted to cover a substantial portion of the innercap 710 and the end bracket 690 that is exposed to the internal air ofthe motor 610. Since the bearings 670 are encased within the inner cap710 and the end bracket 690, the thermal barrier 740 acts to insulatethe bearings 670 from the heated internal air of the motor 610. Themotor 610 can also include a thermal barrier 750 disposed inside themotor 610 for insulating the opposite drive side bearing assembly 680from the heat generated by a motor core 625. The thermal barrier 750 isprovided to ensure that the opposite drive side of the motor 610 remainscool in absence of a fan for providing cooling directly to the oppositedrive side of the motor 610. The thermal barrier 750 is mounted to theinner cap 720 and adapted to cover a substantial portion of the innercap 720 and the end bracket 700 that are exposed to the internal air ofthe motor 610. Since the bearings 680 are encased within the inner cap720 and the end bracket 700, the thermal barrier 750 acts to insulatethe bearings 680 from the heated internal air of the motor 610.

A first external airflow source 735 is provided at the drive side of themotor 610 and a second external air source 745 is provided at theopposite drive side of the motor 610. The external airflow source 735and 745 can be any of an external fan or an external blower.Alternatively, both ends of the motor can be cooled by convection, suchthat the external air sources 735 and 745 are air from the environmentsurrounding the motor 610. Such an arrangement may realize advantages inan application utilizing free convection cooling, where no external fanis present. However, one may also realize advantages to using a thermalbarrier at each end of the motor in combination with one or more fans orblowers.

In view of the foregoing structural and functional features describedabove, two methodologies in accordance with various aspects of thepresent invention will be better appreciated with reference to FIGS. 9and 10. While, for purposes of simplicity of explanation, themethodologies of FIGS. 9 and 10 are shown and described as executingserially, it is to be understood and appreciated that the presentinvention is not limited by the illustrated order, as some aspectscould, in accordance with the present invention, occur in differentorders and/or concurrently with other aspects from that shown anddescribed herein. Moreover, not all illustrated features may be requiredto implement a methodology in accordance with an aspect the presentinvention.

FIG. 9 illustrates one particular methodology for fabricating a totallyenclosed motor in accordance with an aspect of the present invention.The methodology begins at 850 where a motor electrical core coupled to ashaft is provided. The electrical core includes a stator and a rotor. At860, the electrical core and shaft are inserted and mounted in agenerally cylindrical frame to enclose the motor core and protect itfrom the environment. At 870, thermal barriers are mounted to at leastone of the inner caps and end brackets. At 880, bearing assemblies aredisposed between end brackets and inner caps. The end brackets areprovided to further enclose the motor from the environment. Themethodology then proceeds to 890 where the end brackets are coupled tothe motor frame. At 900, a cooling system is provided at the motoropposite drive end to supply the motor with cooling air and dissipateheat produced by the electrical core. At 910, an air deflector ismounted to the opposite drive end of the motor to capture externalcooling air and direct it as high velocity air over the end bracket,thereby, cooling the bearings supported within the end bracket.

FIG. 10 illustrates one particular methodology for facilitating coolingof a totally enclosed motor in accordance with an aspect of the presentinvention. The methodology begins at 920 where a bearing assembly isinsulated from heat generated by the motor core. A thermal barrier maybe employed to insulate the bearing assembly located at the drive end ofthe motor, the bearing assembly located at the opposite drive end of themotor, or both bearing assemblies. At 930, cooling air is providedalongside the outside surface of the motor frame. The cooling air may beprovided by an external fan, an external blower, or by free convection.At 940, cooling air is redirected over an outer side of one or both ofthe bearing assemblies, which may be accomplished by an air deflector.

Although the invention has been shown and described with respect to acertain preferred embodiment or embodiments, equivalent alterations andmodifications will occur to others skilled in the art upon reading andunderstanding this specification and the annexed drawings. In particularregard to the various functions performed by the above describedcomponents (systems, assemblies, systems, etc.), the terms used todescribe such components are intended to correspond, unless otherwiseindicated, to any component which performs the specified function of thedescribed component (i.e., that is functionally equivalent), even thoughnot structurally equivalent to the disclosed structure which performsthe function in the herein illustrated exemplary embodiment orembodiments of the invention. In addition, while a particular feature ofthe invention may have been described above with respect to only one ofseveral embodiments, such feature may be combined with one or more otherfeatures of the other embodiments, as may be desired and advantageousfor any given or particular application. Furthermore, to the extent thatthe term “includes” is used in either the detailed description or theclaims, such term is intended to be inclusive in a manner similar to theterm “comprising”.

What is claimed is:
 1. A system that facilitates cooling of a totallyenclosed motor, comprising: an electrical core that provides energy tothe motor, the electrical core generating heat during normal operationof the motor; a motor shaft coupled to the electrical core; a frame thatsurrounds and supports the electrical core; a first bearing assemblylocated at a drive end of the motor to support the motor shaft, thefirst bearing assembly mounted between an inner cap and an end bracket;and a thermal barrier comprising a gasket, the thermal barrier disposedbetween the core and an inner side of the first bearing assembly tosubstantially insulate the first bearing assembly from the heatgenerated by the electrical core.
 2. The system of claim 1, furthercomprising a second thermal barrier disposed between the core and aninner side of a second bearing assembly that is located opposite to thedrive end of the motor, the second thermal barrier substantiallyinsulates the second bearing assembly from the heat generated by theelectrical core.
 3. The system of claim 2, wherein the second thermalbarrier comprises a gasket, which gaskets of the first and secondthermal barriers are annular.
 4. The system of claim 1, wherein thethermal barrier is mounted to an inside surface of the inner cap and theend bracket.
 5. The system of claim 1, further comprising an airdeflector disposed on an outer side of the first bearing assembly tocapture a portion of cooling air forced over an outside surface of themotor from an airflow source, and direct the cooling air over the outerside of the first bearing assembly.
 6. The system of claim 5, whereinthe airflow source is at least one of an external fan and an externalblower.
 7. The system of claim 1, wherein the thermal barrier comprisesan inner cap thermal barrier and an end bracket thermal barrier eitheror both of which are formed of one of a metal and a fiberglass.
 8. Thesystem of claim 7, wherein the gasket couples the inner cap thermalbarrier to the end bracket thermal barrier.
 9. The system of claim 7,wherein the gasket accounts for a variation in tolerance between theinner cap thermal barrier and the end bracket thermal barrier.
 10. Thesystem of claim 7, wherein the gasket forms an airtight seal between theinner cap thermal barrier and the end bracket thermal barrier.
 11. Thesystem of claim 1, wherein the thermal barrier comprises an annularinner cap thermal barrier and an annular end bracket thermal barrier,the annular inner cap thermal barrier is mounted to and substantiallysurrounds a portion of the first inner cap that is exposed to theinternal air of the motor, and the annular end bracket thermal barrieris mounted to and substantially surrounds a portion of the first endbracket that is exposed to the internal air of the motor, so that thefirst bearing assembly is insulated from the heat generated by theelectrical core.
 12. A method for cooling a totally enclosed motor, thetotally enclosed motor includes an electrical core, the core coupled toa motor shaft, and a frame that encloses the electrical core, the coregenerates heat during normal operation of the motor, the methodcomprising: providing a first bearing assembly located at a drive end ofthe motor to support the motor shaft, the first bearing assembly mountedbetween an inner cap and an end bracket; insulating the first bearingassembly from the heat generated by the core using a thermal barrier;forcing cooling air along the outside surface of the motor frame; andredirecting the cooling air over an outer side of the first bearingassembly.
 13. The method of claim 12, further comprising disposing thethermal barrier between the electrical core and an inner side of thefirst bearing assembly.
 14. The method of claim 12, further comprisingmounting the thermal barrier on the end bracket and the inner cap, thethermal barrier substantially surrounding the end bracket and the innercap.
 15. The method of claim 12, further comprising, providing a secondbearing assembly opposite the drive end, the second bearing assemblymounted between a second inner cap and a second end bracket; coupling anouter side of the second bearing assembly to the second end bracket andan inner side of the second bearing assembly to the second inner cap;and mounting a second thermal barrier having an annular gasket on thesecond end bracket and the second inner cap to substantially surroundthe second end bracket and the second inner cap to insulate the secondbearing assembly from the heat.
 16. The method of claim 12, furthercomprising mounting the thermal barrier on the end bracket and the innercap, the thermal barrier comprises an inner cap thermal barrier and anend bracket thermal barrier that are joined using an annular gasket. 17.The method of claim 16, wherein the inner cap thermal barrier mounts onthe inner cap and the end bracket thermal barrier mounts on the endbracket.
 18. The method of claim 12, further comprising coupling axiallyextending fins to the end bracket to facilitate cooling of the firstbearing assembly.
 19. The method of claim 18, wherein the cooling air isredirected across the fins using an air deflector.
 20. A system thatfacilitates cooling a totally enclosed motor, the totally enclosed motorincludes an electrical core that is coupled to a motor shaft, and aframe that encloses the electrical core, the core generates heat duringnormal operation of the motor, the system comprising: means forproviding a first bearing assembly located at a drive end of the motorto support the motor shaft, the first bearing assembly mounted betweenan inner cap and an end bracket; means for insulating the first bearingassembly from the heat generated by the core, the means for insulatingincludes thermal barrier means mounted to the inner cap and the endbracket; means for forcing cooling air along the outside surface of themotor frame; and means for redirecting the cooling air over an outerside of the first bearing assembly.